1. Field of the Invention
This invention relates to a disc drive apparatus for recording information signals on and/or reproducing information signals from an optical disc or a magneto-optical disc, a disc drive unit to be mounted in such a disc drive apparatus and an optical pickup device to be mounted in such a disc drive unit.
2. Description of the Related Art
Optical discs, such as CD (compact discs) and DVD (digital versatile discs), are popularly known, and disc drive apparatuses of various different types have been marketed to accommodate such optical discs.
FIG. 1 of the accompanying drawings illustrates schematically a low-profile disc drive apparatus 200 to be mounted in a host appliance that may typically be a notebook type personal computer. The disc drive apparatus 200 comprises a disc tray 202 adapted to be horizontally moved into and out of a cabinet 201 and a disc drive unit 203 mounted on the disc tray 202. Note that, in FIG. 1, the top plate of the cabinet 201 is removed for the purpose of easy viewing.
As shown in FIG. 2, the disc drive unit 203 comprises a disc rotary drive mechanism 204 for driving an optical disc to rotate, an optical pickup 205 for writing signals on or reading signals from the optical disc being driven to rotate by the disc rotary drive mechanism 204, a pickup feed mechanism 206 for feeding the optical pickup 205 in a radial direction of the optical disc, a flexible printed circuit board (to be referred to as FPC hereinafter) 207 that is connected to the optical pickup 205 at an end thereof and folded back toward the bottom surface side of the optical pickup 205 at the other end thereof and a circuit substrate 208 connected to the FPC 207 at the other end of the FPC 207. The above listed components are integrally fitted to a base 209 to realize a super-low-profile structure.
The disc rotary drive mechanism 204 includes a flat spindle motor 211 provided on the top surface thereof with a turntable 210 for receiving an optical disc. The spindle motor 211 is supported by the circuit substrate 208 and adapted to drive the optical disc received by the turntable 210 to rotate.
The optical pickup 205 includes an objective lens 205a for converging the light beam emitted from a semiconductor laser and irradiating the signal recording surface of the optical disc with the converged light beam so as to write a signal onto or read a signal from the optical disc by detecting the returning light beam reflected by the signal recording surface of the optical disc by means of a photo-detector (not shown).
The pickup feed mechanism 206 includes a pair of guide shafts 212a, 212b for movably supporting the optical pickup 205 so as to move the optical pickup 205 in a radial direction of the optical disc, a rack member 213 fitted to the optical pickup 205, a lead screw 214 to be engaged with the rack member 213 and a stepping motor 215 for driving the lead screw 214 to rotate. As the stepping motor 215 drives the lead screw 214 to rotate, the lead screw 214 and the rack member 213 that are engaged with each other by turning drive the optical pickup 205 to move from the outer periphery to the inner periphery of the optical disc or vice versa.
The FPC 207 includes a wiring section 207b connected to the optical pickup 205 and another wiring section 207c connected to the circuit substrate 208, the wiring section 207b and the wiring section 207c being arranged oppositely relative to the folded position 207a of the FPC 207 so as to be held in parallel with each other in the direction of feeding the optical pickup 205 between the optical pickup 205 and the circuit substrate 208. Thus, the FPC 207 is adapted to displace its folded position 207a when the optical pickup 205 is fed in a radial direction of the optical disc, while keeping the wiring section 207b connected to the optical pickup 205 and the wiring section 207c connected to the circuit substrate 208 in the state where they are disposed oppositely relative to the folded position 207a and held in parallel with each other in the direction of feeding the optical pickup 205.
The circuit substrate 208 is a so-called rigid substrate that carries thereon the connector 216 connected to the other end of the above described FPC 207, another connector 217 for electrically connecting the cabinet 201 and another circuit substrate arranged on the disc tray 202 and a drive control circuit (not shown) for controlling the operation of the disc drive unit 203 for driving various related components of the disc drive unit 203.
The base 209 is a piece of metal plate formed by punching to show a predetermined contour. It has a table exposing aperture 218a for exposing the turntable 210 to the outside and a pickup exposing aperture 218b for exposing the optical pickup 205 to the outside that are formed so as to be continued from each other as viewed from one of the main surface sides of the base 209. The circuit substrate 208, the pair of guide shafts 212a, 212b, the lead screw 214 and the stepping motor 215, which are described above, are fitted to the other main surface side of the base 209 along with some other components.
The disc drive unit 203 having the above described configuration is then fitted to the bottom surface of the disc tray 202 as shown in FIG. 1. A disc holding recess 219 having a profile corresponding to that of the optical disc and an aperture 220 for exposing the disc drive unit 203 to the outside through the bottom of the disc holding recess 219 are formed on the top surface of the disc tray 202. A top cover 221 for holding down the FPC 207, which is exposed to the outside through the above described pickup exposing aperture 218b, is fitted to the top surface section of the base 209 in the area where the base 209 is exposed to the outside through the aperture 220 of the disc tray 202. The top cover 221 is provided with a substantially rectangular aperture 222 for exposing the objective lens 205a. The aperture 222 corresponds to the movable range of the optical pickup 205 that is driven to move so as to be fed in a radial direction of the optical disc. On the other hand, a bottom cover 223 for covering the bottom surface side of the drive unit 203 is fitted to the bottom surface of the disc tray 202.
The disc drive apparatus 200, in which the above described disc drive unit 203 is mounted, operates to record an information signal on or reproduce an information signal from the optical disc D in a state where the disc tray 202 that holds the optical disc D is contained in the cabinet 201. More specifically, the optical pickup 205 of the disc drive unit 203 writes a signal on or reads a signal from the optical disc D, while the disc rotary drive mechanism 204 is driving the optical disc D to rotate and the pickup feed mechanism 206 is feeding the optical pickup 205 in a radial direction of the optical disc D.
Meanwhile, in the disc drive apparatus 200 showing such a low profile, the gap between the top cover 221 and the bottom cover 223, which are described above, is made very narrow as a result of reducing the height of the entire apparatus as shown in FIG. 3 so that consequently the wiring section 207b and the wiring section 207c that are folded relative to each other at the opposite side of the folded position 207a of the FPC 207 and sandwiched between the top cover 221 and the bottom cover 223 are forced to show a very reduced height.
As shown in FIGS. 1 and 3, the folded position 207a of the FPC 207 produces a raised part 207d that is raised toward the side of the top cover 221. The raised part 207d that is raised toward the top cover 221 increases the extent of rising when the FPC 207 is folded within a narrow range so that it can come out and project to the outside through the aperture 222 of the top cover 221.
Thus, in the conventional disc drive apparatus 200, the part of the FPC 207 that projects through the aperture 222 of the top cover 221 contacts the signal recording surface of the optical disc D to consequently damage the signal recording surface of the optical disc D when the optical pickup 205 is driven to move so as to be fed in a radial direction of the optical disc D.
Particularly, disc drive apparatuses 200 manufactured and marketed recently are equipped with an optical pickup 205 that is compatible with the different recording formats of different discs, including CDs and DVDs. Additionally, efforts are being mode to make the optical pickups 205 of disc drive apparatus 200 compatible with the recording format of BDs (blu-ray discs) which can highly densely record signals. Further, the FPC 207 is provided with signal lines necessary for driving and controlling the optical pickup 205 in any of the different recording formats. In other words, the FPC 207 of such a disc drive apparatus 200 carries a large number of wires that inevitably make the FPC 207 show a high profile. Then, there can arise the problem that the part of the FPC 207 that cannot be covered by the top cover 221 comes out to the outside through the aperture 222 of the top cover 221.